Attosecond Precision Multi-km Laser-Microwave Network

Abstract

Synchronous laser-microwave networks delivering attosecond timing precision are highly desirable in many advanced applications, such as geodesy, very-long-baseline interferometry, high-precision navigation and multi-telescope arrays. In particular, rapidly expanding photon science facilities like X-ray free-electron lasers and intense laser beamlines require system-wide attosecond-level synchronization of dozens of optical and microwave signals up to kilometer distances. Once equipped with such precision, these facilities will initiate radically new science by shedding light on molecular and atomic processes happening on the attosecond timescale, such as intramolecular charge transfer, Auger processes and their impact on X-ray imaging.Here, we present for the first time a complete synchronous laser-microwave network with attosecond precision, which is achieved through new metrological devices and careful balancing of fiber nonlinearities and fundamental noise contributions. We demonstrate timing stabilization of a 4.7-km fiber network and remote optical-optical synchronization across a 3.5-km fiber link with an overall timing jitter of 580 and 680 attoseconds RMS, respectively, for over 40 hours. Ultimately we realize a complete laser-microwave network with 950-attosecond timing jitter for 18 hours. This work can enable next-generation attosecond photon-science facilities to revolutionize many research fields from structural biology to material science and chemistry to fundamental physics.

Timing and Synchronization in Large-Scale Facilities

“…Demonstration of sub-femtosecond timing distribution was achieved with the lasermicrowave network shown in Fig. 6a utilizing polarization maintaining and stabilized fiber links [1]. The timing signal from the master laser is distributed through a network that contains two independent fiber links of 1.2-km and 3.5-km length operated in parallel.…”

“…Remote laser synchronization over 44 hours without interruption is within 100 as RMS (blue). Overall, an unprecedented long-term precision of 670 as RMS for the out-of-loop drift over 18 hours (black) is achieved [1].…”

“…Master-laser (OMO) jitter characterization setup (PBS, polarization beam splitter; DBS, dichroic beam splitter; DM, dichroic mirror; PPKTP, periodically-poled KTiOPO4; PI, proportional-integral controller; BPD, balanced photodetector; PZT, piezoelectric transducer; SSA, signal source analyzer)[1].…”

“…Timing and synchronization system for an XFEL[1]. Measured master-laser jitter spectrum and corresponding integrated timing jitter[6].…”

“…Local optical-optical synchronization measurement results. (a) Out-of-loop jitter spectrum; (b) long-term timing drift (sampling rate: 2 Hz); (c) timing drift spectrum[1].…”